Bahrain’s government has vowed to forcefully confront demonstrators who are planning to take to the streets on Wednesday, to demand political change after the failed “Pearl revolution” near the start of the Arab spring, in 2011.

“The government will forcefully confront suspect calls to violate law and order and those who stand behind them through decisive measures,” the official Bahrain news agency quoted him as saying.

Emergency decrees have banned demonstrations in Manama, the capital, and imposed other new restrictions on dissent and freedom of expression.

Khalifa, a hardliner who now overshadows the once influential and moderate crown prince, described the government being “at a critical stage” in the struggle to “eliminate terrorism”.

Maryam al-Khawaja, of the Bahrain Centre for Human Rights, said that more than 100 homes in the Manama area had experienced night-time raids recently “to spread terror” before the protests, which mark independence from Britain in 1971.

“They are closing off entire residential areas so they can control who comes in or out,” Khawaja said. “The regime is preparing for a very violent crackdown.” Villages had been “caged in with barbed wire”, she added.

Bahrain’s new Tamarrod (which means rebellion in Arabic) movement uses the same name as the popular coalition that campaigned against the Egyptian president and Muslim Brotherhood leader, Mohamed Morsi.

Tamarrod has called on the US and Britain, Bahrain’s principal western allies, to end their support for King Hamad Al Khalifa. Critics say the Sunni Muslim dynasty is failing to address the grievances of the Gulf island state’s restive Shia majority.

Washington and London back calls for reforms made by an independent commission of enquiry and occasionally protest at the use of unusually repressive measures — such as a total ban on demonstrations or the punitive removal of citizenship. But Bahrain houses the headquarters of the US fifth fleet and is a significant international offshore financial centre. It is also the backyard of neighbouring Saudi Arabia, the region’s biggest oil producer.

Bahrain’s government and opposition groups have discussed their differences in reconciliation talks that were launched last February but the dialogue has yet to produce any significant results.

Mansour al-Jamri, editor of the independent newspaper al-Wasat, said:”There was optimism a month ago but all of a sudden the mood changed. At the moment it’s gloom again. It’s a very volatile situation. We might be heading for a very harsh period.” Activists estimate that 300 – 400 people were arrested during Ramadan.

Al-Wefaq, the main Shia opposition movement, is not part of Tamarrod. It supports peaceful protests to achieve a constitutional monarchy but it has often been at odds with more radical groups such as the Bahrain Freedom Movement, which demands the removal of the royal family.

The government regularly accuses its opponents of working with Iran. But apart from propaganda in Iranian state media there is no independent evidence of this.

“The international community is not willing to discuss the fall of the Al Khalifa even though it did support the revolutions in Egypt and Libya and provided help to the Syrian rebels,” Ali al-Fayez, a youth activist, told a London news conference. “But the Al Khalifa have proved they are not capable of reform.”

Last weekend, the Bahraini authorities deported a US teacher accused of writing for “radical groups”. Blogger Mohammad Hassan Sudayf and photographer Hussain Hubail, both in detention, have reportedly been tortured and charged with “inciting hatred against the regime,” calling for illegal gatherings and “inciting people to ignore the law”.

Amnesty International said Sudayf’s lawyer was arrested last week for tweets saying that he had seen torture marks on his client and revealing the charges both men face.

• This article was amended on 14 August 2013 to correct errors in a subheading and in the text. The subheading stated that democracy activists were planning to mark the anniversary of the “failed Pearl revolution of 2011″ and Ali al-Fayez was described as a “former Bahraini MP” in the body of the story.